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ECE 442 Communication System Design Lecture 1. Modulation

ECE 442 Communication System Design Lecture 1. Modulation. Husheng Li Dept. of EECS The University of Tennessee. Course Information. Lecturer: Husheng Li Time: 12:40pm --- 1:55pm Location: MK404 Office time: 3pm --- 4pm, everyday Office: MK644 Course website

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ECE 442 Communication System Design Lecture 1. Modulation

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  1. ECE 442 Communication System DesignLecture 1. Modulation Husheng Li Dept. of EECS The University of Tennessee

  2. Course Information • Lecturer: Husheng Li • Time: 12:40pm --- 1:55pm • Location: MK404 • Office time: 3pm --- 4pm, everyday • Office: MK644 • Course website http://web.eecs.utk.edu/~husheng/ECE442_2012.htm

  3. Textbook • A. B. Carlson and P. B. Crilly, Communication Systems, 5th edition, McGraw Hill, 2010

  4. Reference Book (1) • J.Proakis and M. Salehi, Digital Communications, 5th Edition, McGraw Hill, 2008

  5. Reference Book (2) • A. Goldsmith, Wireless Communications, Cambridge, 2005

  6. Reference Book (3) • D. Tse and P. Viswanath, Fundamentals of Wireless Communication, Cambridge, 2005

  7. Logistics • Grading: midterm/final tests (50%), homework (4 problems each week, 25%), projects (totally 3, 25%) • Projects: • Project 1: Use Matlab Simulink to simulate the performance of a communication system (deadline: midterm) • Project 2: Use Matlab to implement the coding and decoding algorithms of convoulutional codes. Evaluate the performance (deadline: April 15th). • Project 3: A report about 4G systems (deadline: Final exam)

  8. Coverage

  9. Digital Modulation / Demodulation • Modulation means loading digital information bits into the continuous waveforms at the transmitter. Demodulation is the inverse procedure. • When a sinusoidal signal is used for radio emission, the information can be carried at the three elements: amplitude (amplitude-shift keying: ASK), frequency (frequency-shift keying: FSK) and phase (phase-shift keying: PSK).

  10. Illustration

  11. Bandpass Signal • Any modulated bandpass signal can be writtend in the following quadratic-carrier form: • The equivalent lowpass spectrum is defined as

  12. Amplitude Modulation • An M-ary ASK signal can be written as • A special case is called OOK.

  13. Spectrum Efficiency • The spectrum efficiency is given by

  14. QAM • Quadrature-carrier AM (QAM) achieves twice the spectrum efficiency of binary ASK Signal Constellation

  15. Phase Modulation • An M-ary PSK signal is expressed in general by which can be decomposed into the quadrature form. QPSK 8-PSK

  16. Frequency Modulation • In FSK, the frequency is given by

  17. Spectrum of FSK • The i and q elements of Sunde’s FSK are mutually independent. • Sunde’s FSK has very little spillover.

  18. M-ary Orthogonal FSK and CPFSK • For the M-ary orthogonal FSK, the M keyed frequencies are spaced by • In CPFSK, the information signal is the RF signal is then given by

  19. Coherent Binary Systems • A coherent bandpass system employs information about the carrier frequency and phase at the receiver to detect the message. • A noncoherent system does not need synchronization with the carrier phase, thus causing performance degradation compared with coherent bandpass system.

  20. Bandpass Binary Receiver • The filter for optimum binary detection should be matched to the difference between the two signaling waveforms.

  21. Two Alternative Approaches Parallel matched filter Correlation detector

  22. How to Analyze the Bit Error Rate? • When the two possible outputs are z1 and z0, the bit error rate is given by

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